1. Field of the Invention
The present invention relates to an image reading apparatus, an original reading method and an original conveyance apparatus, and particularly relates to an image reading apparatus for reading each of a plurality of images recorded on an original to be read such as a photographic film, to an original reading method and to an original conveyance apparatus usable for the image reading apparatus.
2. Description of the Related Art
Conventionally, an image processing system is known, in which film images recorded on a photographic film are read by an image reading apparatus including image forming means and an image sensor such as a CCD, and after variously processing resulting image data by correcting it or otherwise, the image is recorded on a recording medium or displayed on a display unit. The photographic film as referred to herein indicates a film with a negative or positive image made visible by developing processing after photographing a subject.
A conventional image reading apparatus of an image processing system of this type used for reading film images comprises preliminary reading (hereinafter referred to as the prescan) means for reading an image with comparative rapidity with a low definition using a film carrier (original conveyance apparatus) for conveying a photographic film in such a manner that each of a plurality of film images recorded on a photographic film passes sequentially through a predetermined reading position, which preliminary reading is for the purpose of increasing the image reading speed, means for determining reading conditions for main reading (hereinafter referred to as the fine scan) for reading an image at a comparatively low rate with a high definition based on the image data obtained by the prescan and various image processing conditions for the image data obtained by the fine scan, and means for conducting the fine scan on the image data and for processing the image data obtained by the fine scan under the processing conditions thus determined.
On the other hand, photographic films to be read are of several types including size 135 and size 240. In order to enable a single image reading apparatus to read a plurality of these photographic films, a film carrier is prepared for each type of photographic film and changed according to the type of the photographic film.
A conventional image reading apparatus using a plurality of film carriers as described above is available in which film images are located at predetermined reading positions for the respective types of the film carrier and focusing is controlled in such a manner that the image-forming position determined by image-forming means and the image sensor position coincide with each other, and the values for the focusing point obtained by the focusing control are stored for each of a plurality of optical magnifications. When reading a plurality of film images continuously, the value for the focusing position corresponding to the optical magnification of each film image is read from the values of the focusing points for each of a plurality of optical magnifications and at least one of the image-forming means a nd the image sensor are moved.
On the other hand, Japanese Patent Application Laid-open JP-A No. 9-211558 discloses a technique intended for obtaining high-quality image data, comprising an image-forming lens unit having dual functions of magnification adjustment and focusing adjustment (focusing control), in which the focusing is controlled after the magnification adjustment of the image-forming lens unit, after which the magnification of the image-forming lens unit is corrected in accordance with the focusing control. In this way, the focus is controlled accurately, and a projected image of a predetermined size is obtained with an accurate optical magnification, thereby producing a suitable print of high image quality free of vignetting of the lenses.
The technique in which the values of the focusing point are stored for each of a plurality of optical magnifications for each film carrier, however, requires as many focusing control sessions as the optical magnifications for all the film carriers. This gives rise to not only the problem of a considerable time consumed but the problem that a great storage capacity is required due to the requirement that the values of the focusing point obtained from the focusing control are stored for each optical magnification for each film carrier.
The technique disclosed in JP-A No. 211558 described above, on the other hand, poses the problem that for a plurality of images having different optical magnifications to be read continuously with high image quality, the focusing control is required for each image, thereby making high-speed image reading impossible.
An object of the present invention, which has been developed in order to resolve the problems described above, is to provide an image reading apparatus capable of shortening processing time without need of a large storage capacity and capable of producing high-quality image data, an image reading method and an original conveyance apparatus capable of using the image reading apparatus.
In order to achieve the object described above, according to a first aspect of a first invention, there is provided an image reading apparatus comprising: a light source for illuminating the light on an original to be read having a plurality of images recorded thereon; conveyance means for conveying the original to be read in such a manner that each of the plurality of images passes through a predetermined reading position sequentially; image-forming means for focusing the light transmitted through the original to be read or the light reflected from the original to be read; an image sensor for separating each of the plurality of images recorded on the original to be read into a plurality of pixels, reading the pixels and outputting the pixels as image data; moving means for moving at least one of at least one portion of the image-forming means, the image sensor, and the original to be read along the optical axis direction of the image-forming means; storage means for storing a first value of a focusing point for each of a plurality of optical magnifications and for storing at least one of at least one second value, which is obtained by controlling the moving means in such a manner as to control the focusing for at least one predetermined optical magnification of the plurality of the optical magnifications for an object located at the reading position, and a difference of the second value and the first value at the predetermined optical magnification with respect to the second value, the first value being obtained by controlling the moving means in such a manner as to control the focusing to attain a coincidence between the image-forming position of a reference object which image-forming position depends on the image-forming means and the position of the image sensor for each of the plurality of optical magnifications; and control means for controlling the moving means in such a manner that at least one of at least one portion of the image-forming means, the image sensor and the original to be read moves to a position based on the first value and on one of the difference and the second value, which are stored in the storage means, at the time of reading one of a portion and the whole of the plurality of images.
With the image reading apparatus according to the first aspect, the original to be read having the plurality of images recorded thereon is illuminated with a light source, the original to be read is conveyed by conveyance means in such a manner that each of the plurality of images passes sequentially through the predetermined reading position, the light transmitted through the original to be read or the light reflected from the original to be read is focused by the image-forming means, and each image recorded on the original to be read is separated into a plurality of pixels by the image sensor and output as image data. Further, examples of the original to be read include a transmissible original such as a photographic film and a reflective original such as a photographic print. Also, examples of the image sensor include a line CCD, an area CCD and photoelectric conversion elements other than the CCD.
The image-forming means can use a lens or a group of lenses, but a zoom lens, whose optical magnification can be changed by moving one portion of lenses, may also be used. In cases where the lens or the group of lenses is used, the entirety of the image-forming means is moved, but if the zoom lens is used, only a portion of the image-forming means is moved.
Also, the image reading apparatus according to the first aspect comprises the moving means capable of moving at least one of at least one portion of the image-forming means, the image sensor, and the original to be read along the optical axis direction of the image-forming means, wherein the first value for the focusing point is stored in the storage means for each of the plurality of optical magnifications and at least one of at least one second value and the difference of the second value and the first value for a predetermined one of the plurality of optical magnifications with respect to the second value is stored in storage means, the first value being obtained by controlling the moving means in such a manner that the focusing is controlled to attain coincidence between the image-forming position of the reference object which image-forming position depends on the image-forming means and the position of the image sensor for each of a plurality of optical magnifications, the second value being obtained by controlling the moving means in such a manner that the focusing is controlled for the object at the reading position for at least one predetermined optical magnification of the plurality of optical magnifications. Examples of the object include an image recorded on the original to be read and an object that is a positional reference of the image.
In this way, the difference is added to the first value for each of the optical magnifications stored in the storage means to obtain thereby the value for the focusing point for each of the plurality of the optical magnifications of the object located at the reading position.
In a case where the difference is not stored by the storage means and only the second value is stored, the difference can be obtained by calculating the difference between the second value and the first value for the optical magnification corresponding to the second value.
Further, in the image reading apparatus according to the first aspect, the moving means is controlled by the control means in such a manner that at least one of at least one portion of the image-forming means, the image sensor and the original to be read moves to a position based on the first value, and the second value or the difference which are stored in the storage means when reading a portion or the whole of the plurality of images.
Namely, the position obtained by adding, to the first value for an optical magnification of the image that is the original to be read, the difference stored by the storage means in a case where the difference is stored by the storage means, and the difference between the second value and the first value for the optical magnification corresponding to the second value in a case where only the second value is stored by the storage means, is a position corresponding to the focusing point corresponding to the optical magnification of the image that is the object to be read. By setting at least one of at least one portion of the image-forming means, the image sensor and the image to be read to the resulting position, therefore, the image-forming means and the image sensor can be located at the focusing point of the image to be read without carrying out the focusing control.
As described above, with the image reading apparatus according to the first aspect, the value for the focusing point for each of the plurality of optical magnifications of the object located at the reading position can be obtained based on the first value for each of the plurality of the optical magnifications stored in the storage means and on at least one of the difference for at least one of the plurality of the optical magnifications and the second value. Therefore, the need for carrying out the focusing control for each optical magnification of the object located at the reading position is eliminated, and the storage in the storage means can be completed within a short time. At the same time, the focusing point corresponding to the optical magnification of an image to be read can be set by moving at least one of the image-forming means, the image sensor and the original to be read to a position determined based on the first value and either the difference or the second value. It is therefore possible to set the focusing point within a short time as compared with the case in which the focusing point is controlled for each image to be read, with the result that the overall processing time can be shortened.
According to a second aspect of the invention, in the image reading apparatus according to the first aspect, the control means controls the moving means in such a manner that the focusing is controlled for the object with reference to a position based on the first value and on one of the difference and the second value, which are stored in the storage means, before reading one of a portion and the whole of the plurality of images, a third value for the focusing point at the time when the focusing is controlled for the object is stored, and in the case where the optical magnification of the image next to be read is different from the present optical magnification, the moving means is controlled in such a manner that at least one of at least one portion of the image-forming means, the image sensor, and the original to be read is moved to a position based on the first value and the third value.
In the image reading apparatus according to the second aspect, the control means for the image reading apparatus according to the first aspect controls the moving means in such a manner as to control the focusing of the object according to the reference position based on the first value stored in the storage means and on one of the difference and the second value prior to reading a portion or the whole of the plurality of images, the third value for the focusing point is stored at the same time, and in the case where the optical magnification of the image next to be read is different from the present optical magnification, at least one of at least one portion of the image-forming means, the image sensor and the original to be read is moved to the position based on the first value and the third value.
As described above, with the image reading apparatus according to the second aspect, the focusing of the object is controlled prior to reading the image, the third value for the resulting focusing point is stored, and in the case where the optical magnification of the image next to be read is different from the present optical magnification, at least one of at least one portion of the image-forming means, the image sensor and the original to be read is moved to a position based on the first value and the third value. Therefore, the optimum focusing point corresponding to the actual reading environment can be set, and the focusing point can be set with higher accuracy than when the focusing point is set without using the third value.
According to a third aspect of the invention, in the image reading apparatus according to the second aspect, the object is provided in the vicinity of a conveyance passage surface of the original to be read in the conveyance means, the apparatus further comprises a limiting member disposed on or in the vicinity of the conveyance means, for limiting the range of displacement of the original to be read along the optical axis direction to twice the depth of field of the image-forming means or less, and the apparatus offsets the distance equal to one half of the range of displacement with respect to a position determined according to the first value and the third value.
With the image reading apparatus according to the third aspect, the object in the image reading apparatus according to the second aspect is disposed in the vicinity of the conveyance passage of the original to be read in the conveyance means, the range of displacement of the original to be read along the optical axis direction is limited to not more than twice the depth of field of the image-forming means by the limiting member disposed on or in the vicinity of the conveyance means, and the distance equal to one half of the range of displacement is offset with respect to a position determined in accordance with the first value and the third value.
As described above, with the image reading apparatus according to the third aspect, the object for the image reading apparatus according to the second aspect is disposed in the vicinity of the conveyance passage of the original to be read in the conveyance means, and the range of displacement of the original to be read along the optical axis direction is limited to not more than twice the depth of field of the image-forming means by a limiting member disposed on or in the vicinity of the conveyance means, while at the same time offsetting the distance equal to one half the range of displacement with respect to a position determined by the first value and the third value. Even in the case where the position of the original to be read along the optical axis direction is displaced to a maximum degree, the deviation of the focusing point from the correct focusing point for the image recorded in the original to be read is limited within a range accommodated in the depth of field of the image-forming means, with the result that an image of high quality can be produced reliably.
With an image reading apparatus according to a fourth aspect of the invention, in the image reading apparatus according to the second aspect, the storage means further records as a fourth value a difference in position with respect to the optical axis direction between the original to be read and the object; and the controlling means, in a case where the optical magnification of the image next to be read is different from the present optical magnification, controls the moving means so as to move at least one of at least one portion of the image-forming means, the image sensor, and the original to be read, to a position based on the first value, the third value, and the fourth value.
With the image reading apparatus according to the fourth aspect, the difference in position with respect to the optical axis direction between the original to be read and the object is stored as the fourth value by the storage means in the image reading apparatus according to the second aspect. Namely, the first value, at least one of the difference and the second value, and the fourth value are stored by the storage means.
Further, with the image reading apparatus according to the fourth aspect, the controlling means according to the second aspect, in a case where the optical magnification of the image next to be read is different from the present optical magnification, controls the moving means so as to move at least one of at least one portion of the image-forming means, the image sensor, and the original to be read to a position based on the first value, the third value, and the fourth value.
In this way, with the image reading apparatus according to the fourth aspect, the storage means according to the second aspect further stores the difference in position with respect to the optical axis direction between the original to be read and the object, and the controlling means effects control such that at least one of at least one portion of the image-forming means, the image sensor, and the original to be read is moved to a position based on the first value, the third value, and the fourth value. As a result, in comparison with a case in which the fourth value is not applied, a more accurate focusing point can be set.
In an image reading apparatus according to a fifth aspect, in the image reading apparatus according to either the first aspect or the fourth aspect, when processing using the first value is carried out, the first value is used after being corrected in accordance with a difference between the present temperature and a temperature when the first value is obtained.
With the image reading apparatus according to the fifth aspect, in the image reading apparatus according to either the first aspect or the fourth aspect, when processing using the first value is carried out, the first value is used after being corrected in accordance with the difference between the present temperature and a temperature when the first value is obtained.
The focusing point is changed in accordance with temperature at a gradient corresponding to the optical magnification. As a result, there is variation in the first value in cases in which there is a temperature difference between the time the first value is obtained and the time when processing using the first value is carried out. Accordingly, in the present fifth aspect, correction based on the temperature difference is carried out in order to correct the difference in the first value caused by the temperature difference.
In this way, in the image reading apparatus according to the fifth aspect, in either the first aspect or the fourth aspect, when processing using the first value is carried out, the first value is used after being corrected based on the temperature difference between that time and the time the first value was obtained. Thus, in comparison to a case in which this correction is not carried out, a more accurate focusing point can be set.
According to a sixth aspect of the invention, in the image reading apparatus according to the first aspect, a plurality of the conveyance means corresponding to the types of the original to be read is comprised; wherein the storage means stores at least one of the difference and the second value for each of a plurality of the conveyance means.
As described above, with the image reading apparatus according to the sixth aspect, the conveyance means according to the first aspect is provided for each type of the original to be read, at least one of the difference and the second value for each conveyance means is stored in the storage means, the focusing is controlled only once for each conveyance means, and there is as a minimum only one value(at least one of the difference and the second value) stored for each conveyance means. As compared with the case where the focusing is controlled for each optical magnification for each conveyance means to store thereby the value for each focusing point, therefore, less time is consumed for the focusing control and the storage capacity for storing the value for the focusing point can be reduced.
According to a seventh aspect of the invention, in the image reading apparatus according to either the second or the third aspect, a plurality of the conveyance means corresponding to the types of the original to be read is comprised; wherein the storage means stores at least one of the difference and the second value for each of a plurality of the conveyance means, and the control means stores the third value for the conveyance means used.
As described above, with the image reading apparatus according to the seventh aspect, the conveyance means according to either the second or third aspect is provided for each type of the original to be read, the storage means stores at least one of the difference and the second values for each conveyance means, the control means stores the third value for the conveyance means to be used, the focusing is controlled only once for each conveyance means, and there is as a minimum only one value (at least one of the difference and the second value) to be stored for each conveyance means. Thus, as compared with the case in which the focusing is controlled for each optical magnification for each conveyance means and the value for each focusing point is stored, the time consumed for the focusing control can be shortened and the storage capacity for storing the value for the focusing point can be reduced.
In an image reading apparatus according to an eighth aspect, in the image reading apparatus according to either the first aspect or the seventh aspect, the object is used as the reference object.
In this way, with the image reading apparatus of the eighth aspect, the object is used as the reference object in either the first aspect or the seventh aspect. Thus, in comparison with a case in which the reference object and the object are prepared separately, the cost of preparing the reference object can be reduced.
By the way, the image reading method according to the present invention exhibits a function and an effect similar to those of the first invention.
According to a first aspect of a second invention, there is provided an original conveyance apparatus for conveying an image recorded on an original to be read mounted in an image reading apparatus to a predetermined reading position, comprising an object that can be read by the image reading apparatus and is a reference for controlling the focusing of the image at a position other than a conveyance passage for the original to be read.
As described above, the original conveyance apparatus according to the first aspect of the second invention comprises the object that is a reference for controlling the focusing of an image that can be read by the image reading apparatus and recorded on the original to be read at a position other than the conveyance passage for the original to be read. Therefore, the effect of warping or the like of the original to be read at the time of controlling the focusing of the image directly can be removed. Thus image data of high quality can be produced while at the same time making it possible to control the focusing while reading the image recorded on the original to be read.
Also, with the original conveyance apparatus according to the second aspect of the second invention, in the original conveyance apparatus according to the first aspect, one each of the object is disposed on both sides of the conveyance passage of the original to be read.
As described above, with the original conveyance apparatus according to the second aspect, an effect similar to that of the first aspect is exhibited, and one each of the object is disposed on both sides of the conveyance passage of the original to be read according to the first aspect. By setting the central portion of each focusing point of each object as the focusing point of the original to be read, therefore, the focusing point of a main object generally located substantially at the center of the original to be read can be determined reliably even in the case where the original conveyance apparatus is loaded in the image reading apparatus in a state of being tilted in the direction perpendicular to the direction of conveyance of the original to be read.